View Full Version : Digital preview for LF cameras

Brian C. Miller
27-Feb-2013, 10:25
Just had the thought: want digital preview for your scene? Put a white sheet of paper or plastic in a film holder, and mount a tiny camera to the inside of your lens board.

There are tiny cameras now (really, really tiny!) that would take up very little space on a lens board. The DOF is huge, so the lens wouldn't have to be realigned as the lens board goes through its movements. You'd be able to tell when you're running out of coverage, and you could dial in coarse focus fairly quickly.

C. D. Keth
27-Feb-2013, 10:45
What does that do that a groundglass can't?

Brian C. Miller
27-Feb-2013, 11:13
It would be good for portrait sittings, so the sitter can see what's happening. Also, stuff happening in the corners can really sneak up on you. Some people on the forum go through a lot of instant film. A solution like this is a modest substitute.

7-Mar-2013, 03:00
Brian, Great trick !! Did you already tried?

I would expect 0.180 micron white PET sheet to sell at more price than polaroid 55 ;)

Anyone knows where to find this material?

What does that do that a groundglass can't?

I think about this ones:

- Non reversed image (without bulky mirror).
- Actual film-holder focusing.
- No need to carry lupe, no need to carry dark-cloth. (just the iPhone, or electronic viewfinder).

Also for testing equipment:

- Light leaks check (but maybe not the weakest ones).
- Easy adjust "ground-glass focus" (without developing any film.)
- Help to create marks in ground glass for different film-holders, roll-film holders (4x5, 6x7, 6x9, ....)

Miniaturization nowadays is amazing. Can a lens board be made with a small camera on the back and also work together with a lightweight display, smartphone, or electronic viewfinder? Why not?

Nathan Potter
7-Mar-2013, 09:41
Brian, I like the potential of doing this. Might be especially good for very wide angle lenses where the way off axis rays at the image corners are about impossible to see through the GG. A piece of white paper forms a real image with a different radial reflection falloff than GG.

I think you would need a bit of decent resolution to do critical focusing and mounting the video camera off axis would be awkward. Maybe the interjection of a thin beam splitter on the optical axis would be convenient for viewing the image orthogonal to the view direction.

Nate Potter, Austin TX.

Brian C. Miller
7-Mar-2013, 09:44
Actually, white plastic is quite easy to purchase. I buy from Tap Plastics (http://www.tapplastics.com). They have 4-mil window film (link (http://www.tapplastics.com/product/window_films/window_tint_films/frosted_window_film/324)) which would slide right in.

As for trying it as a system, no, not yet. I was given a camera pen, and that got me thinking about this. The pen is a 4Gb USB stick with a 640x480 camera in it, which can do stills or movies. So that's what inspired this. I haven't done too much research, but it does seem good enough for seeing what's on the back.